Posts Tagged: Diabrotica undecimpunctata

Some folks mistake the spotted cucumber beetle for a ladybug or lady beetle.

However, unlike the beneficial ladybug, which devours aphids and other soft-bodied insects, the spotted cucumber beetle is a major agricultural pest. The adults, yellowish-green with black spots, feed on the leaves of cucumbers, melons, cotton, beans and ornamentals and can spread viruses. The larvae stunt the roots of corn and other plants.

Its name is a mouthful: Diabrotica undecimpunctata (which has probably appeared on national spelling bees). True to its name, Diabroticacan be rather diabolical in your vegetable garden or flower bed.

Insect photographers often like to focus on its color and character.

But look closely and you'll also see its path of destruction.

Spotted cucumber beetle and its path of destruction. (Photo by Kathy Keatley Garvey)

Spotted cucumber beetle and its path of destruction. (Photo by Kathy Keatley Garvey)

The Western spotted cucumber beetles (Diabrotica undecimpunctata) is one of California's most common insects. And though quite attractive in coloring, it's a major agricultural pest.

"Come in, my pretty," is probably what a witch would say during the Halloween season.

Retired UC Berkeley entomologist Jerry Powell, in his book, California Insects (co-authored by Charles Hogue), describes the adult as "bright green with six variable black spots on each wing cover and variable amounts of black on (the) legs and underside."

"They eat leaves and flowers of all kinds except conifers; (they're) particularly abundant on plants of the squash family."

They're found throughout California, except at the highest elevations, he says.

But have you ever seen this insect take flight?

We recently watched a spotted cucumber beetle crawl beneath a tangerine leaf and vanish. Suddenly, like a submarine periscope, its antennae appeared, twitchy rapidly. Then its head popped up.

That huge dark object (camera!) startled it, though. It took flight, landing a few feet away on the sidewalk.

With its wing covers open, it looked very much like a polka-dotted airplane on a runway.

The assassin bug (Zelus renardii) is a force to be reckoned with, especially when it comes to a spotted cucumber beetle (Diabrotica undecimpunctata).

The assassin bug wears no white hat but it should. A cunning predator, it lies in wait and stabs an unsuspecting prey with a lethal toxin powerful enough to paralyze and dissolve tissue.

Then it's all over but the feeding.

The assassin bug sort of looks like a cartoon character, with its beady eyes, long beak (proboscis) and its long, slender antennae.

The spotted cucumber beetle looks a little like a ladybug (aka lady beetle) except for its coloration. It's a 12-spotted greenish-yellow insect. And a pest. Diabrotica dines on young, tender plants like cucumbers, squash, pumpkins and melons (cucurbits). It also transmits a virus.

So it was the good guy vs. the bad guy. Zelus vs. Diabrotica.

This time the good guy won.

That loud cheering sound you hear is from all the melon growers out there.